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Safety and compatibility of magnetic-controlled growing rods and magnetic resonance imaging
Henry R Budd1, Oliver M Stokes2, Judith Meakin3
1Exeter Spine Unit, Princess Elizabeth Orthopaedic Centre, Royal Devon and Exeter NHS Foundation Trust, Barrack Road, Exeter, UK. henry.budd@hotmail.com.
Purpose:
Magnetically controlled growth rods (MCGRs) are a new technology for the management of early-onset pediatric deformity enabling guided spinal growth by controlling the curvature. These rods contain a rare earth magnet and are contraindicated for MRI. We have investigated the behavior MCGRs to determine whether MRI adversely affects rod properties and to determine the extent of image distortion.
Methods:
This is an in vitro experiment using two magnetic growth rods secured in a 1.5 T MRI. A gradient echo sequence MRI was performed to evaluate whether the rods elongated, contracted or rotated during scanning and a phantom model was used to evaluate the amount of artifact induced.
Results:
The rod was not activated or subsequently impaired by the process of MRI. Image distortion of 28.9 cm along the long axis of the magnet and 20.1 cm perpendicular to this was seen with extension 10.6 cm cranial to the magnet housing. No negative effect was demonstrated on the magnetic rod elongation mechanism.
Conclusions:
This study has demonstrated that there are no detrimental effects of MRI on the MCGR and imaging of the head and neck phantom can still be interpreted. Further in vivo study is warranted.
Insights
Magnetic growth rods (MCGRs) are safe for MRI scans. This study found no adverse effects on rod function or elongation, ensuring continued use in pediatric spinal deformity management.
Area of Science:
- Orthopedic Surgery
- Biomedical Engineering
- Radiology
Background:
- Magnetically controlled growth rods (MCGRs) offer guided spinal growth for pediatric deformities.
- MCGRs contain magnets and are typically contraindicated for MRI due to potential interference.
- Investigating MRI's effect on MCGRs is crucial for patient management.
Purpose of the Study:
- To assess MRI's impact on MCGR properties and function.
- To quantify image distortion caused by MCGRs during MRI.
- To determine if MRI affects the magnetically controlled elongation mechanism.
Main Methods:
- In vitro experiment with two MCGRs in a 1.5 T MRI scanner.
- Gradient echo sequence MRI to evaluate rod elongation, contraction, and rotation.
- Phantom model used to measure MRI artifact induction.
Main Results:
- MRI did not activate or impair the MCGRs.
- Significant image distortion observed: 28.9 cm axial, 20.1 cm perpendicular.
- No detrimental effects on the magnetic rod elongation mechanism were found.
Conclusions:
- MRI poses no detrimental effects on MCGRs.
- Imaging of head and neck phantoms with MCGRs remains interpretable.
- Further in vivo studies are recommended to confirm findings.
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Description of the Procedures
Computed Tomography (CT) scan:
Computed Tomography (CT) scans use X-ray technology to generate detailed images of bones, organs, and tissues. During the scan, the patient lies on a moving table...